Means for determining unbalance in rotary workpieces

ABSTRACT

A disc shaped indicia bearing reference target with a conically shaped permanent magnet adapted to be received in a centering hole of a ferromagnetic rotary workpiece to be balanced on a balancing machine wherein the target may be quickly affixed and removed and be repeatedly used.

111w Sfiafies ateni [151 3709943 Schmidt 1451 Jan. 9, 1973 [54] MEANS FOR DETERMINING 3,016,037 1/1962 Smith .;.....1 16/124 7 UNBALANCE IN ROTARY 2,992,489 7/1961 Kurrcls 4.33/16) WORKPIECES v v Primary Examiner-Richard C. Queisser [72] Inventor: William G. Schmidt, 4733 Shaffer Assistant Examiner Herbert Goldstein Ave., Madison, Wis. 53716 Atmmey Keith Schoff [22] Filed: May 11, 1970 57 ABSTRACT [21] App1.No.: 36,353 1 A disc shaped indicia bearing reference target with a comically shaped permanent magnet adapted to be U-S. received in a centering hole of a ferromagnetic rotary Int. Cl. workpiece to be balanced on a balancing machine [58] Field of Search ..73/466, 467, 487; 335/285 wherein the target may be quickly affixed and removed and be repeatedly used.

[56] References Cited UNITED STATES PA'I'EN'TS Z CIaIms, 1 Drawing Figure 2,487,035 11/1949 Weaveretal "73/4661 APAIENIEDJZM 9mm 3.1091643-v INVENTOR. WILLIAM G. SCHMIDT v .ATTQ EY' I MEANS FOR DETERMINING UNBALANCE IN ROTARY WORKPIECES This invention relates to a method and-means for lessening the time required for balancing a rotary workpiece on a balancing machine, and more particularly relates to target means for referencing the angle of 2 front face and truncated conically configured permanent magnet portion 21 unitarily affixed to disc portion 20 and projecting from the rear face thereof. Target 17 is operably placed in position for use by inserting magnet portion 21 into hole 19 so that the surfaces of the hole and the magnet fay or at least engage at the basal plane of the conically configured members to provide stable alignment between the axes of shaft 18 and target 17. For use with a centering hole having'a 60 apex angle, it is preferred to provide magnet portion 21 with-an apex of similar angle: the apex of magnet portion 21 is truncated tov prevent debris or impershow the angle of unbalance, angular reference being made to the indexing marks. The application and removal of paint or marked tape on workpieces is time consuming, bothersome and wasteful of labor and material, and can beavoided by repetitive use of a simple, quickly manipulated indexing magnet.

it is an object of this invention to provide a method and means for quickly providing reference indicies on a rotary workpiece to be balanced on a balancing machine.

It is a further object of this invention to provide indicia bearing target means which can be easily manipulated and attached to workpieces and repetitively used.

Other objects will become apparent from the following detailed description and the drawing in which FIG.

1 is a perspective view in partial cutaway of means of this invention shown together with a portion of a balancing machine. I I

Referring to FIG. 1, workpiece 10, shown to be an electric motor armature, is supported in V. shaped bearings 11, moveably mounted on blocks 12. Blocks 12 are supported to be operably moveable transversely t0 the axis of rotation of workpiece in response to forces of rotationalunbalance in workpiece 10 about its axis of rotation, rotational unbalance occuring when the mass center of the workpiece is not coincident with the rotational axis. Electromagnetically induced currents are generated by movement of blocks 12, and energize stroboscopic' lamp 13. Belt is frictionally engaged with workpiece l0 and is driven by electric motor drive means, not shown, to rotate workpiece 10 at operable speeds which ordinarily are from about 1,000- 2,000 rpm, oscillatory movement of blocks 12 occuring at similar frequency, in case of unbalance in the workpiece, with stroboscopic lamp 13 being energized at the same frequency. If desired, a photocell together with a rotatable. slit aperture may be provided to precisely register the rotational angle at which lamp l3 flashes, or target 17 may be view visually, but in eithercase, the reading is referenced with respect to indicia on target 17. The foregoing is descriptive of confection in the bottom of hole 19 from interferring with proper seating of magnet portion 21 in hole 19, but it is not necessary that magnet portion 21 be truncated.

To set up the machine, workpiece 10 is inserted through the loop formed by endless belt 15 and placed with the ends of shaft 18 in bearings 11, blocks 12 havingbeen adjusted to operably position bearings 11 for receiving the shaft. Target 17 is placed with magnet portion 21 disposed in hole 19 with-the attraction of magnet for steel or other ferromagnetic material causing the magnet to be firmly retained when workpiece 10 is driven at speeds of several'thousand revolutions per minute.An optimum size and configuration for target 17 is an aluminum disc of about 2 inches diameter:

and 0.01 inch thickness with numerals printed peripherally on the front face of the disc and a magnet adhered to the back face of about 36inch basal diameter and shaped as a truncated cone. Anysuitable magnetized material may be usedfor the magnet and any other suitably strong'material than aluminum may be used for the disc including magnetized or ferromagnetic material. Dimensions of the target may be as great as desired limited only by dynamic forces which would cause the target to slip at operable rotational speeds.

During operation of the balancing machine, indicia observed in the illumination of stroboscopiclamp 13 serves to reference the rotational position of workpiece 10 with respect to the lateral displacement of blocks 12 at a given moment so as to enable a derivativecompuv of unbalance in static balancing procedures as well as i in dynamic balancing, and other similar operations will ventional practice and constitutes no part of this invention.

workpiece 10 comprises ferromagnetic shaft 18 supported in bearings 11 with conical centering hole 19, ordinarily. having about a apex angle, disposed in the end of shaft 18. Such centering holes are typically present in workpieces which have been machined on a lathe or the like. Target 17 as shown is partially cutaway and disposed in axial alignment with shaft 18, and comprises disc portion 20 having an indicia bearing be suggested to one skilledin the art from the foregoing disclosure in which the means of this invention can be used and all such obvious usesand equivalents are included in the scope of this invention. If desired, the conical magnet portion and the disc shaped face portion of the target described herein may be non-unitary, the only requirement being that they rotate unitarily. Thus, the face portion may fit around or over the magnet portion, the required function of the magnet being to keep the indicia bearing face portion axially centered with'respect to rotation to preventit from being dislodgedfrom theworkpiece by centrifugal force.

Iclaim: 1. A new method for using a dynamic balancing machine in which electromagnetic generating means rotation, the steps of centering on said rotational axis dicia bearing face by said stroboscopic lamp means,

by disposing at least partially within and contacting at least-the basal peripheral edge of said pilot hole, a substantially conically configured permanent magnet car- .rying a substantially planar reference indicia bearing a face free of contact with the workpiece and disposed substantially perpendicular to the rotational axis,- operably rotating said workpiece, illuminating said inviewing said reference indicia to reference the radial angle of unbalance in said workpiece.

2. Target means for use with a balancing machine comprising in combination a substantially conically configured permanent magnet portion adapted to be disposed with its axis coincident with the axis of rotation of a workpiece to be balanced and substantially planar indicia bearing face portion unitary with said magnet portion and disposed substantially perpendicular to 'said axis of said magnet portion and disposed free of contact with said workpiece. 

1. A new method for using a dynamic balancing machine in which electromagnetic generating means induces energizing currents in stroboscopic lamp means in response to unbalance being sensed during rotation of a workpiece, wherein the workpiece comprises a ferromagnetic end extremity with a pilot hole disposed therein axially coincident with the axis of rotation, the steps of centering on said rotational axis by disposing at least partially within and contacting at least the basal peripheral edge of said pilot hole, a substantially conically configured permanent magnet carrying a substantially planar reference indicia bearing face free of contacT with the workpiece and disposed substantially perpendicular to the rotational axis, operably rotating said workpiece, illuminating said indicia bearing face by said stroboscopic lamp means, viewing said reference indicia to reference the radial angle of unbalance in said workpiece.
 2. Target means for use with a balancing machine comprising in combination a substantially conically configured permanent magnet portion adapted to be disposed with its axis coincident with the axis of rotation of a workpiece to be balanced and substantially planar indicia bearing face portion unitary with said magnet portion and disposed substantially perpendicular to said axis of said magnet portion and disposed free of contact with said workpiece. 